Membrane protein insertion and secretion in bacteria.

Export of secretory proteins across and insertion of membrane proteins into the cytoplasmic membrane of Escherichia coli and other bacteria is mediated by the enzyme complex translocase. The last decade has seen a major advance in the understanding of the mechanism of these processes. A large part of this progress can be attributed to the development of general and powerful methods to study the translocase activity in vitro. Here we describe a transcription-translation method used to analyze the insertion of membrane proteins into E. coli inner membrane vesicles and a rapid and quantitative fluorescent method to analyze the translocation of secretory proteins.